In the production of bottles with thermoplastic sleeve labels that are heat shrunk about the bottle sidewall, shoulder and heel areas, it has been the practice to form the sleeves from label blanks that are wound on a cylindrical mandrel with the trailing edge overlapping the leading edge. The overlap is engaged by a heated sealing bar and forms a heat sealed seam extending the height of the sleeve. The sleeve is then telescoped over the bottle and the assembled sleeve and bottle are passed through a heat tunnel with bottle and sleeve being rotated to expose the full circumference of the sleeve to the heat to evenly shrink the label and cause it to conform to the exterior configuration of the bottle. The sleeves may be positioned with their lower margins below the bottom of the bottles, in which case the sleeve will be shrunk over the heel and the bearing surface as well. Such a process and apparatus is disclosed in U.S. Pat. No. 3,802,942 issued Apr. 9, 1974.
A more recent U.S. Pat. No. 4,574,020, issued Mar. 4, 1986, discloses a method and apparatus for applying heat shrinkable, thermoplastic wrap-around labels to containers by providing a web of foamed polystyrene sheet material which is subsequently cut into label lengths equal to the circumference of the containers plus an overlap seam area. The web of material is held to the surface of a rotating vacuum drum and, as the drum rotates about its vertical axis, the web is cut into label length. With the label adhering to the vacuum drum surface, the outer surface of the web is brought into contact with a rotating gravure roll which has a gravure pattern that contains a solvent for the material and will apply the solvent to finite areas of the leading and trailing edge of the label. With the solvent applied to the label, the label is brought into rolling contact with a container where the leading edge of the label adheres to the container and with the container rolled along the label surface, the trailing edge will overlap and become sealed to the leading edge by the solvent action.
In the operation of the above system, one of the most critical aspects is the precise transfer of the solvent from the gravure roll to the surface of the label. If the gravure roll surface and the label surface do not make proper contact, there will not be sufficient solvent applied to the label in order to dissolve the label so as to make it adhere to the bottle or container as it comes into contact therewith and transfers thereto. Likewise, as the label trailing edge overlaps the leading edge, it is absolutely necessary that the trailing edge will have received a full height strip of solvent applied thereto so that a complete overlap seam will be formed. This seam has to be complete since subsequent heat shrinkage of the label about the bottle will open the seam up and produce a defective label if the seam is not sealed throughout its full height.
The label carrying vacuum drum has sets of raised areas or pads on its periphery which will underlie the leading and trailing edges of the label and the rotating gravure roll will be set to engage the label at these critical points in the relative rotation of the drum and roll. The gravure roll is normally mounted on a platform which is shiftable about a vertical axis which is parallel to the axis of the roll. Such a gravure roll mounting system is disclosed in copending U.S. patent application Ser. No. 856,241, filed of even date.
In order to insure that the solvent is properly applied, the gravure roll must carry a sufficient quantity of solvent on its surface pattern. The use of a vertical fountain biased against the gravure roll is shown in U.S. Pat. No. 4,574,020, issued Mar. 4, 1986. This patent discloses a fountain which requires considerable down time in order to change the fountain. It is necessary to change fountains as they become worn or become contaminated with extraneous materials.
With the foregoing in view, it is an object of the present invention to provide a solvent applicating fountain which can be easily and quickly exchanged for one in service when required, resulting in a minimum of disruption in the operation of the labeling machine.
The quick change fountain of the invention is mounted on a vertical plate which may be removed from its holder and replaced by another fountain mounted on a similar plate without requiring the use of any tools to effect the mounting.
Other and further objects will be apparent from the following description taken in conjunction with the attached sheets of drawings.